Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$86.32	10.317%	$95.2256	$95.23	$95.25	$95.20
Purchase #2	$56.89	11.521%	$63.4443	$63.44	$63.45	$63.40
Purchase #3	$29.95	13.190%	$33.9004	$33.90	$33.90	$33.90
Purchase #4	$10.32	5.821%	$10.9207	$10.92	$10.90	$10.90
Purchase #5	$187.75	13.329%	$212.7752	$212.78	$212.80	$212.80
Purchase #6	$74.73	10.553%	$82.6163	$82.62	$82.60	$82.60
Purchase #7	$34.60	6.661%	$36.9047	$36.90	$36.90	$36.90
7 purchase totals =	$480.56		$535.7872	$535.79	$535.80	$535.70